The invention relates to an apparatus for strapping articles, with a band guiding frame which surrounds the article with a distance, and the band channel of which comprises a cover on the side facing the article, which can be opened over its entire length and which closes automatically, which consists of profile strips of an elastic material which are secured to the band guiding frame and which comprise a side wall and a front wall, which overlaps the side of the band channel facing the article at least partially with a distance from the channel base, wherein the profile strips are secured at the band guiding frame beyond the free edges and the base of the band channel and are provided with wear and/or sliding elements at least in the region of the band contact surfaces formed at the front wall. The invention is further directed to a profile strip, in particular for covering the band channel in the band guiding frame of an article strapping apparatus, wherein the profile strip comprises a side wall and a front wall, which are angled to one another and which are manufactured in one piece of an elastic material with a high fatigue strength under reversed bending, and which is provided with wear and/or sliding elements in the region of the band contact surfaces formed at the front wall.
Strapping apparatuses for articles which are to be surrounded with a metal or particularly a plastic band are known in different embodiments. In addition to so-called hand devices, stationary strapping machines are available, where the strapping band is first injected into the band channel at the band guiding frame surrounding the article to be strapped, and then exits from the band channel on the inner side facing the article during the manufacture of the strapping. The band channel is thereby covered by profile strips which are designed in a flexible manner, and can thereby clear the channel at the inner side facing the article, if a tensile force is exerted on the strapping band lying in the band channel during the lashing around the article.
With the strapping apparatuses used currently, the band channel is covered by angled metal strips having a short length, which are arranged at the two side walls of the band guiding frame in a jointed manner and are held pressed by helical springs in a resting position closing the band guiding channel, whereby they can tilt outwardly against the effect of the helical springs when the strapping band is drawn against the article and is tightened. As the covering profile flaps are in fact mounted in an elastic manner, but are inelastic themselves, they open and close by the tension of the strapping band directed inwardly not gradually but abruptly and along their entire length, whereby the exit of the strapping band from the band channel takes place in an irregular manner and with a large noise emission. As the spring tension at the mountings of the individual flaps can hardly be adjusted in an even manner, the covering flaps develop different clamping forces along the band guiding frame and let the strapping band leave the channel at different locations of the band guiding frame which cannot be determined beforehand during the band tensioning procedure. It is also often a problem that the side and face walls of the metal flaps are not in alignment at their abutting surfaces, but that stepped transitions are generated there, with which the strapping band, which is injected into the band channel, can abut with its front transverse edge, which results in failures.
For avoiding the above-mentioned disadvantages with the strapping apparatuses used up to now, it has been suggested in the generic DE 199 12 940 A1, to replace the covering flaps consisting of metal strips with a profile strip of an elastic material, which can cover the band channel at its inner side in respectively one piece, so that abutting surfaces are no longer present in the cover. As the profile strip itself is elastic, it respectively opens the band channel only immediately in the region in which the band has to leave the band channel during its tightening around the article, and closes it again immediately behind it.
The practical implementation of this basically excellent suggestion known from DE 199 12 940 has proved to be more difficult than expected. The strapping band which is drawn radially inwardly from the band channel during the strapping procedure, effected a high wear of the profile strips at the wall contact surfaces formed at their front faces, so that even reasonably acceptable service lives of the profile strip could not be achieved without wear and/or sliding elements provided there, which consist of a particularly wear-resistant material. The wear and sliding elements of polytetrafluoroethylene (PTFE) or a coploymer therefor suggested by DE 199 12 940, which were to be produced with the remainder of the profile strip, had the disadvantage to reduce the flexibility of the profile strip considerably, so that a prompt closure of the band channel after the exit of the strapping band could not be achieved with this.